FV214 Conqueror The FV214 Conqueror, also known as "Tank, Heavy Gun No 1 120 mm Conqueror" was a British Main Battle Tank of the post-war era, sometimes classified as a heavy tank. It was developed as a response to the Soviet Josef Stalin IS-3 heavy tanks and carried a larger 120 mm gun compared to the contemporaneous Centurion's 20-pounder (83.4 mm). Its role was to provide long range anti-tank support for Centurion tanks.